How does the pitot-static system work and what instruments does it feed?

The pitot-static system measures air pressure to provide flight data. The pitot tube faces forward to measure total (stagnation) pressure, while static ports on the fuselage measure static (ambient) pressure. The difference is dynamic pressure, proportional to airspeed squared. This system feeds: Airspeed indicator (uses dynamic pressure), Altimeter (uses static pressure with ISA calibration), Vertical speed indicator (rate of static pressure change), and Air data computer. Blockage from ice or debris causes erroneous readings, so aircraft have redundant systems, pitot heat, and alternate static sources.